RV Water Heater Pressure Relief Valve Dripping
On this page (5 sections)
The Short Answer: Some dripping from an RV water heater’s relief valve while the tank heats is normal. Suburban explains that an RV plumbing system is closed, so heated water has nowhere to expand and pressure rises until the valve opens at 150 psi. Restoring the air pocket at the top of the tank reduces it. Constant dripping when cold, or a steady stream, is not normal. Never plug the valve.
Why an RV relief valve drips
The valve opens if the water reaches 210°F or the pressure reaches 150 psi. In a house, water can expand back into the street main or an expansion tank. In an RV, the pump’s check valve or the city-water inlet’s check valve closes the system. Suburban’s manual (opens in a new tab) says that during heating the pressure will reach 150 psi, the valve will drip until pressure falls, and that this condition “is normal and does not indicate a defective relief valve.”
The tank is designed to hold a small air pocket at the top that acts as a cushion. Everyday use gradually absorbs it, and the dripping becomes more frequent.
Restoring the air pocket (Suburban procedure)
Suburban gives these owner steps:
- Turn off the water heater (gas and electric).
- Turn off the cold-water supply (pump off, city water off).
- Open a hot faucet inside the RV.
- Pull out the relief valve handle and let water flow from it until it stops.
- Release the handle; it should snap closed.
- Close the faucet and turn the water supply back on. As the tank fills, the air pocket forms.
Repeat when the dripping returns. Letting the tank cool first makes step 4 safer.
When dripping is not normal
| Observation | Likely cause | Next step |
|---|---|---|
| Drips only while heating, stops when hot | Normal expansion | Restore air pocket |
| Drips constantly on city water, even when cold | High campground pressure | Use a pressure regulator at the hose |
| Keeps dribbling after the handle was lifted | Debris or scale holding the seat open | Operate once more; replace the valve if it persists |
| Steady stream with very hot water | Overheating: thermostat or control fault | Turn off both heat sources; RV technician |
| Valve body or threads wet, not the outlet | Threaded joint leak | Valve resealed or replaced |
Reducing it long term
Suburban recommends against installing a check valve directly at the water heater inlet, because that increases weeping. If restoring the air pocket does not help enough, the manual suggests an expansion or accumulator tank in the cold-water line between the tank and the check valve; an RV dealer can install one.
A replacement relief valve must match the original rating. Do not install a valve between the relief valve and the tank, and never plug or cap it.
Related: RV water heater leaking outside, relief valve leaking after testing, and relief valve stuck open.
Frequently Asked Questions
Q: Do Atwood/Dometic heaters drip the same way? A: The same expansion happens in any closed RV system, so expansion dripping happens on other brands too. Check your heater’s manual for its own guidance on the air pocket and relief valve.
Q: Will a water pressure regulator stop the dripping? A: It stops drips caused by high city pressure. It does not stop expansion dripping while heating, because that pressure comes from inside the closed system.
Manuals and supporting references
These links distinguish general safety information from model-specific documentation. A manual directory helps you locate your unit’s instructions; it does not establish that every model uses the same parts, codes, or test values.
- Suburban: SW10D/SW10DE/SW10DM/SW10DEM installation and operation manual (copy hosted by Forest River) (opens in a new tab)Suburban SW10 models: relief valve rating, normal weeping, air-pocket procedure, and check-valve and expansion-tank advice.
- Suburban: service and support (opens in a new tab)Identify the appliance behind the RV badge and obtain its operating instructions.
- A. O. Smith technical bulletin 45: thermal expansion (opens in a new tab)Background on pressure rise in a closed water system. Pressure testing and repairs are professional work.
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